Project Abstract In order to effectively implement universal antiretroviral therapy (ART) for all people living with HIV, new models of care with greater efficiencies in service delivery are needed. A differentiated care framework is being widely recommended, with services tailored to patient needs. However, current models of differentiated care provide expedited services for patients after they have demonstrated several months of timely visits with high adherence. This strategy does not reduce time in clinic during the first few months of care, when most attrition occurs. The principles of behavioral economics suggest that immediate fast-track care will provide superior outcomes, if it is conditional on timely visits. According to the behavioral economics framework, people's choices are affected by systematic and predictable biases. One of these biases is the tendency to perceive losses (loss of fast-track care) as more significant than equivalent gains (the possibility of gaining fast-track care with timely visit attendance). Another is the tendency to exhibit present-biased time preferences, which make it less likely that patients with minimal HIV symptoms will prioritize activities to obtain ART. These biases will be exacerbated in the presence of scarcity of resources. In the proposed R34 grant, we will develop and test a strategy of immediate fast-track care. The study population will include adult patients with WHO Stage 1 or 2 disease. Participants will be randomized to immediate fast-track or standard (deferred fast-track) care. All participants will receive same-day HIV testing and ART initiation prior to study enrollment. The intervention group will receive immediate fast-track care, which is conditional upon timely visits, and after 24 weeks in care, an undetectable viral load (HIV-1 RNA <200 copies/ml). The standard group will be eligible to start fast-track care at 24 weeks, if they have an undetectable viral load. Participants in either group who are >5 days late for any fast-track visit will lose fast-track care for that visit; those in either group with detectable viremia on their 24-week viral load test will be evaluated by a physician, with frequent follow-up visits until they have an undetectable viral load. Three specific aims are proposed. The first aim is to conduct formative research including focus groups with patients and providers to further refine our understanding of facilitators and barriers to retention and ART adherence with fast-track care. The second aim is to develop and test manuals, measures, and procedures for immediate and standard care. The third aim is to conduct a randomized pilot trial of immediate fast-track vs. standard care to assess the feasibility and preliminary effectiveness of immediate fast-track care. Assessments will include viral load testing, self-reported measures of psychosocial correlates of adherence and retention in care as well as perceived value of fast-track care, consideration of future consequences, time in clinic, and cost of services. The primary outcome is retention in care with viral suppression at 48 weeks after HIV testing. If immediate fast-track care is effective, it could serve as a model for HIV treatment in other resource-poor settings.